Effect of Fungal Treatment on the Nutritive Value of Wheat Straw and its Use in the Diet of Dairy Cattle

Abstract

Experiments were conducted to study the growth ability and potential of some
Pleurotus fungi to biodegrade wheat straw and to determine the effect of fungal
treatment on the nutritive value of straw and its use in the diet of dairy cow. The
results showed that there is a potential application of the fungi on wheat straw.
Among the six cultures of Pleurotus, P-41, P-21, P-60 and P-31 had a significantly
(P<0.05) higher growth ability on wheat straw. Supplementation of wheat straw
with 1 or 2% urea nitrogen did not enhance the colonisation and growth rate of the
fungi.
Fungal treatment decreased NDF and ADF, increased the CP and nutrient
digestibility of wheat straw. However, the cultures P-30, P-41 and P-60 showed
significantly (P<0.05) higher ability to degrade the cell wall components of the
straw and improved the IVDMD, IVOMD and in sacco degradability. Treatment of wheat straw with Pleurotus (P-41) either before (FTWS) or after
mushroom production (SPWS) resulted in a significantly (P<0.05) higher amount of
nutrient intake (DMI, OMI and DOMI) when fed to bulls. The digestibility of DM
and OM increased by more than 10% unit in the treated straw as compared to the
untreated wheat straw. In comparison to the untreated straw, feeding fungal treated
wheat straw resulted in a higher ruminal pH and ammonia nitrogen concentration
that indicated an improvement in rumen fermentation. Improvement of nutritive
value was higher in FTWS than the SPWS.
In a feeding trial, four diets containing 0, 10, 20 and 30% fungal (P-41) treated
wheat straw was fed to lactating cows. They showed similar intake of DM, OM,
DOM, CP, TDN and NEL• All diets resulted in similar milk yield and milk
composition, but the diets that contained 20 and 30% treated straw produced a
significantly (P<0.05) higher body weight gain. However, the best animal
performance and feed efficiency were obtained when the treated straw was included
at 20% of the total diet or 40% of the roughage.
When two diets containing 30% of untreated or fungal treated wheat straw were fed
to late lactating cows, higher nutrient digestibility and intake of DM, OM, CP and
ME were observed in the cows fed treated straw. There was 13% increase in FCM
yield by cows fed treated straw. Daily body weight gain was 2.7 times in the
treated straw diet as compared to the untreated straw group. Improvement in the
animal performance reflects the availability of more digestible organic matter and
energy from the wheat straw treated with the fungus.